An interesting, aberrant Arhopala

[atronox]

The diagnostic ID for A. avanthina is that the FW basal cellspot is absent.
In the image all three cellspots are present. ie. one at cellend, one at mid cell & the 3rd basal (actual position is sub-basal).

Could this be variable? D'abrera figures a specimen with the basal cell spot

[Psyche]

Could this be variable? D'abrera figures a specimen with the basal cell spot

The key in C&P4 is quite specific in this differentiation.

Still , this should be easy to test.

The upperside FW border is a thread in the male A. kurzi.
https://singapore.biodiversity.onlin...doptera-000440

The upperside border in A. avathina is much wider , 1mm.
https://m.singapore.biodiversity.onl...doptera-000436


TL Seow: Cheers.

[Banded Yeoman]

Dr Seow, Aaron, thanks for your views on this one. I continue to learn.

The feature of fw basal spot missing is unhelpful in my limited opinion. Even the holotype of A. avathina clearly shows fw sub-basal spots - and if the characteristic truly was regarding the basal spot, which is sometimes discernable in very pristine examples of muta, kurzi etc, it is often too faint to use as a distinguishing feature.

I would be hesitant to id this one as A. kurzi.

It now becomes clear that even in A. kurzi, the sub-marginal spots are rather dark and defined. From all valid A. kurzi specimens that I've seen, however, the forewing band is distinctively broken at each vein for spots 4, 5 and 6. These are specimens with upperside confirmation.

A. avathina, in the holotype from Singapore, displays fw post-discal spots very well aligned. This is also seen in CJ's shot (post 9).

Dr Seow, your point of separating these 2 species by upperside is definitely the most solid method. They prove to be very similar on the underside.

[Psyche]

Dr Seow, Aaron, thanks for your views on this one. I continue to learn.

The feature of fw basal spot missing is unhelpful in my limited opinion. Even the holotype of A. avathina clearly shows fw sub-basal spots - and if the characteristic truly was regarding the basal spot, which is sometimes discernable in very pristine examples of muta, kurzi etc, it is often too faint to use as a distinguishing feature.

I would be hesitant to id this one as A. kurzi.

It now becomes clear that even in A. kurzi, the sub-marginal spots are rather dark and defined. From all valid A. kurzi specimens that I've seen, however, the forewing band is distinctively broken at each vein for spots 4, 5 and 6. These are specimens with upperside confirmation.

A. avathina, in the holotype from Singapore, displays fw post-discal spots very well aligned. This is also seen in CJ's shot (post 9).

Dr Seow, your point of separating these 2 species by upperside is definitely the most solid method. They prove to be very similar on the underside.

If you look at the heading in the link, it says Arhopala avathina avathina Corbet 1941.
Corbet was the author of A. avathina & he wrote the key first based on his holotype specimen.
The image is too blur & vague to say there is a FW basal spot.
https://m.singapore.biodiversity.onl...doptera-000436
My point is if there is a basal spot in this holotype then Corbet would not have written otherwise.

The 2nd point to note is that FW postdiscal spot in space 3 is when fully developed extend towards the base ie elongate horizontally in A. kurzi.

3rdly A kurzi was recorded in Singapore, and as a species is not rare as in A. avathina.




TL Seow: Cheers.

PS. Having a close scrutiny of the image od A. avathina, there does seem to be a basal spot on the left side FW.
Unfortunate there also is a label of Hewitson's A. hypomuta. This raise a question of whether there is a mixup with the specimen.